BACKGROUND OF THE INVENTION
This invention relates to ophthalmological surgery techniques which employ an ultraviolet laser used to provide ablative photodecomposition of the surface of the cornea in order to correct vision defects.
Ultraviolet laser based systems and methods are known for enabling ophthalmological surgery on the external surface of the cornea in order to correct vision defects by the technique known as ablative photodecomposition of the cornea. In such systems and methods, the irradiated flux density and exposure time of the cornea to the ultraviolet laser radiation are so controlled as to provide a surface sculpting of the cornea to achieve a desired ultimate surface change in the cornea, all in order to correct an optical defect. Such systems and methods are disclosed in the following U.S. patents and patent applications, the disclosures of which are hereby incorporated by reference: U.S. Pat. No. 4,665,913 issued May 19, 1987 for xe2x80x9cMethod for Ophthalmological Surgeryxe2x80x9d; U.S. Pat. No. 4,669,466 issued Jun. 2, 1987 for xe2x80x9cMethod and Apparatus for Analysis and Correction of Abnormal Refractive Errors of the Eyexe2x80x9d; U.S. Pat. No. 4,732,148, issued Mar. 22, 1988 for xe2x80x9cMethod for Performing Ophthalmic Laser Surgeryxe2x80x9d; U.S. Pat. No. 4,770,172 issued Sep. 13, 1988 for xe2x80x9cMethod of Laser-Sculpture of the Optically Used Portion of the Corneaxe2x80x9d; U.S. Pat. No. 4,773,414 issued Sep. 27, 1988 for xe2x80x9cMethod of Laser-Sculpture of the Optically Used Portion of the Cornea; U.S. patent application Ser. No. 109,812 filed Oct. 16, 1987 for xe2x80x9cLaser Surgery Method and Apparatusxe2x80x9d; and U.S. patent application Ser. No. 081,986 filed Aug. 5, 1987 for xe2x80x9cPhotorefractive Keratectomyxe2x80x9d.
The art has now advanced to the stage at which self-contained laser based systems are sold as stand alone units to be installed in a surgeon""s operatory or a hospital, as desired. Thus, hospitalization is not necessarily required in order to perform such ophthalmological surgery. Such systems typically include a p.c. (personal computer) type work station, having the usual elements (i.e., keyboard, video display terminal and microprocessor based computer with floppy and hard disk drives and internal memory), and a dedicated microprocessor based computer which interfaces with the p.c. work station and appropriate optical power sensors, motor drivers and control elements of the ultraviolet laser, whose output is delivered through an optical system to the eye of the patient. In use, after the patient has been accommodated on a surgery table or chair, the system is controlled by the operator (either the surgeon or the surgeon and an assistant) in order to prepare the system for the delivery of the radiation to the patient""s eye at the appropriate power level and spatial location on the corneal surface. Patient data is typically entered, either manually via the p.c. work station keyboard or from a memory storage element (e.g., a floppy disk), and the system automatically calculates the beam delivery parameters and displays the resulting calculations on the video display terminal, with an optional hard-copy printout via a suitable printer. The laser is also prepared to deliver the appropriate radiation in accordance with the calculated beam delivery parameters, and the delivery system optics are likewise preconditioned. In some systems, a provision is made for permanently recording on a plastic card made of PMMA (polymethylmethacrylate) a spot image of the laser beam used in the surgical operation. This spot is recorded prior to the operation to ensure that the beam power is properly adjusted and to provide a permanent record of the beam used. PMMA is typically used due to the characteristic of this material of having a closely similar ablative photodecomposition response to that of the human corneal tissue. After the surgery has been performed, the resultant data is typically made part of a permanent record, which becomes part of the patient""s file.
Such systems and methods are presently emerging as the technique of choice for ophthalmological surgery to correct various vision defects in humans. However, as a relatively recent development this technique in general is still subject to close scrutiny and careful evaluation by the medical community as well as by certain regulatory agencies (e.g., the Food and Drug Administration in the United States of America). Although the p.c. work station provides some ability to collect pertinent information for the evaluation of system performance and to aid in tracking the efficacy of the surgical technique, as well as to provide quality control assistance to the manufacturer of the system, existing laser systems lack a simple effective control mechanism for this purpose.
The invention provides a simpe control mechanism for monitoring the actual usage of ophthalmological laser surgery systems, which is relatively inexpensive to implement and highly reliable in tracking information relating to machine usage and patients"" data relating to surgeries performed.
In a first aspect of the invention, an ophthalmological laser surgery system is provided with a patient data card read/write device for controlling and monitoring the operation of the laser surgical system in conjunction with a pre-coded patient data card. The data card and read/write device interact in such a manner that the laser surgical system cannot be operated unless an authorized patient data card is inserted into the read/write device. Once the patient data card is recognized by the system as a legitimate and authorized card, the system is unlocked for normal operation. Preferably, during normal operation the beam delivery parameters calculated by the system, as well as other actual surgical operation data (such as the configuration of the delivery system optics, the duration and power of the laser irradiation of the patient""s cornea, the coordinates of the projected laser beam, and the like) are recorded on the patient data card to form a permanent record independently of or parallel to the information stored in the p.c. work station. Also, a test spot of the actual laser beam can be permanently recorded onto the patient data card by directing the beam onto a preselected region of the data card to perform an ablation of that region.
In another aspect, the invention comprises a patient data card having encoded therein several kinds of information for use in evaluating and controlling a laser based ophthalmological surgery system and surgeries performed therewith. A first type of information comprises an authorization code required by the surgery system for enablement to an operative state. Preferably, this first type of information includes a code unique to a specific laser surgery system so that a given patient data card can be used on one and only one machine. Further information stored on the card identifies all authorized surgeons, the patient, the patient""s past history, the desired prescription or other identifying information regarding the permissible surgery to be performed on that patient, and preoperative diagnostic information for checking the laser system settings. The card may also contain downloadable software for controlling or altering the operation of the laser system. The card may also contain a photograph of the patient, one or more fingerprints of the patient, or a combination of this or other identifier information. In addition, the card preferably contains an ablation region capable of forming and retaining a physical laser ablation imprint of the intended laser treatment for future analysis and comparison.
In use, the card is pre-coded by the system manufacturer or some other control agency, and issued for use with a specific system. If desired, the patient information may be intentionally left blank and provided by the surgeon or some other authorized person prior to the surgical operation. After the surgery has been performed, the actual data pertaining to the surgery is encoded onto the card for future use. Preferably, the data card is issued for a single surgery and is invalidated immediately thereafter, e.g., by permanently recording an invalidation character onto the card.
The data stored on the card can be transferred from the card to any one of a number of interested parties. The surgeon, for example, may transfer the information from the card to a patient data file or some other master file maintained by the surgeon. This can be done at the data card read/write device and the p.c. work station at the site of the laser system. In addition, the information recorded in the patient data card can be transferred to the system manufacturer""s files either from the surgeon""s office using the p.c. work station and a modem, or directly from the patient data card. In the latter case, the card can be physically transferred to the manufacturer""s office by either the surgeon or the patient, or the patient may visit one of a number of convenient sites having a compatible card reader device.
For a fuller understanding of the nature and advantages of the invention, reference should be had to the ensuing detailed description taken in conjunction with the accompanying drawings.